Butanoic acid, 288 Table

Electrophysiologically measured thresholds for butanoic acid and ethanethiol in Manx shearwater Puffinus puffinus) and black-footed albatross Diomedea nigripes) are as low as 0.01 ppm (Wenzel and Sieck, 1966). More electrophysiologi-cal thresholds for some compounds in tree swallows and cedar waxwings (Clark, 1991), starlings (Clark and Smeraski, 1990), and brown-headed cowbirds (Clark and Mason, 1989) are listed in Table 5.4. 

Ruminant milk fats contain a high level of butanoic add (C4 0) and other short-chain fatty acids. The method of expressing the results in Table 3.6 (%, w/w) under-represents the proportion of short-chain adds-if expressed as mol %, butanoic acid represents c. 10% of all fatty acids (up to 15% in some samples), i.e. there could be a butyrate residue in c. 30% of all triglyceride molecules. The high concentration of butyric (butanoic) acid in ruminant milk fats arises from the direct incorporation of jS-hydroxybutyrate (which is produced by micro-organisms in the rumen from carbohydrate and transported via the blood to the mammary gland where it is reduced to butanoic acid). Non-ruminant milk fats contain no butanoic or other short-chain adds the low concentrations of butyrate in milk fats of some monkeys and the brown bear require confirmation. 

On the basis of high FD-factors (Table 3) the sensory significance of 3-methylbutanal and 2-acetyI-l-pyrroIine with malty, roasty odors previously identified as the key odorants in fresh wheat bread crust [21] was established. During storage for 4 days the FD-factors of both odorants decreased significantly, while especially butanoic acid (rancid) and (E)-2-nonenaI remained unchanged. The fatty, green note of the latter odorant especially contributes to the stale note detectable in the overall crust flavor of the stored wheat bread. 

Because inductive effects operate through halogen substitution decreases as the substituent moves farther from the carboxyl. For instance, 2-chlorobutanoic acid has pK = 2.86,3-chlorobutanoic acid has pi a = 4.05, and 4-chlorobutanoic acid has pKa = 4.52, similar to that of butanoic acid itself (Table 20.5). 

Given in Table 5 are aU the calculated distribution coefficients. In these calculations butanoic acid has a calculated group contribution molar volume of 74.66 cm /mol (see Table 3). 

Table 5 indicates that apolar and H-donor type solvents would be poor extraction solvents for butanoic acid. Both the H-acceptor and bi-polar solvents have similar values. Since methyl isobutyl ketone is an H-acceptor solvent and has a proven application extracting another organic acid it seams reasonable to initially explore its use as the solvent for the extraction of butanoic acid from wastewater. It is interesting to note that the model gives a reasonable estimate of the distribution compared to the literature value, also noted in Table 5. 

Doddrell et al. (80, 66) have examined the angular dependence of V(C-C) in a number of aliphatic and alicyclic alcohols. In contrast to the carboxylic acids, 37(C-C) is observed to be a maximum, 5-4 Hz, for a dihedral angle near 0°. For the trans arrangement, — 180°, 3/(C-C) is 3-2 Hz. At dihedral angles of 90 and 270°, 3/(C-C) is less than 0-4 Hz. Observed 3/(C-C) values for the alcohols and carboxylic acids (66, 80, 52) have been compared with values calculated (INDO-FPT) for the model compounds butane, 2-butanol, and butanoic acid. The calculated coupling constants are given in Table V. (80) Also, experimental and calculated 3J(C-C) values for the carboxylic acids are shown in Fig. 2. The calculations, which assumed only the Fermi contact... 

The volatile compounds of these samples were analyzed using SPME-GC-MS. 15 of the compounds included in Table 1 were identified in most samples of at least a group and underwent statistical analysis butane-2,3-dione, acetic acid, 3-methylbutanal, pentanal, hexanal, butanoic acid, hex-( )-2-enal, 3-methylbutanoic acid, heptan-2-one, hept-( -2-enal, octanal, oct-( )-2-enal, 1-octen-3-ol, and non-( )-2-enal. The effect of sodium chloride content, sodium nitrite, added amino acids and reaction time on these compounds is shown below. None of the esters, sulfur and nitrogen containing compounds included in Table 1 could be statistically analyzed. 

The following table brings together data for propanoic acid and butanoic acid and the results, for 25°C, obtained in Worked Problems 8.5 to 8.7. Comment on and interpret these results. 

Carboxymethylamino-4-oxo-3-(4 -aminophenylamino)butanoic acid (3), its ethyl ester (4) and corresponding unsubstituted-aryl analogues (6) and (5) (see Table 6. JO) are fairly potent inhibitors of enkephalinase (K 0.14-0.39 / M) with inibitory potency (K, 15-75 /.iM ) towards aminopeptidase Mil [82]. In the mouse abdominal constriction test, the esters (4) and (5) showed systemic antinociceptive activity with ED50 values of 62 and 81 mg/kg, respectively. In the mouse tail immersion test, both (4) and (5) exhibited antinociceptive activity when administered icv. The results from the mouse abdominal constriction test for compounds (4) and (5) indicated the same rank order of potency as their in vitro inhibitory potency for enkephalinase and aminopeptidase Mil. Another notable observation is that these compounds also exhibited the same rank order in their antinociceptive effects when administered icv alone in the mouse tail immersion test. This direct effect has not been reported for other more potent enkephalindegrading enzyme inhibitors. Compound (4) uniquely exhibited antinociceptive activity when administered subcutaneously in the mouse tail immersion test, an effect which is only partially reversible by naltrexone. This result is in contrast to that for compound (5), which displayed only one third and one quarter of the potency of enkephalinase and aminopeptidase... 

Initial applications of Jqq couplings to amino acid conformation analysis were based on the theoretical finite perturbation theory self consistent field molecular orbital theory at the INDO level of approximation for butanoic acid 25) (Table I). Ptak, et al.(29) noted In their studies of enriched threonine and aspartic acid that application of the butanoic acid couplings did not give agreement with the rotamer populations based on analysis and suggested different values (Table I). We have obtained theoretical results for aspartic... 

Volatile fatty acids p resent in wine may derive from the anabolism of lipids, resulting in compounds with even number of carbon atoms, by oxidative decarboxylation of a-keto acids or by the oxidation of aldehydes. Volatile fatty acids synthesised from a-keto acids are mainly propanoic add, 2-methyl-l-propanoic acid (isobutyric acid), 2-methyl-l-butanoic acid, 3-methyl-l-butanoic acid (isovaleric acid 3-methylbutyric add) and phenylacetic add. From lipid metabolism, the following fatty acids are reported butanoic add (butyric), hexanoic acid (caproic), odanoic acid (caprylic) and decanoic add (capric) (Dubois, 1994). Although fatty adds are charaderized by unpleasant notes (Table 1), only few compounds of this family attain its perception threshold. However, their flavour is essential to the aromatic equilibrium of wines (Etievant, 1991). 

Explain the acidity order in Table 10.4 for butanoic acid and its 2- and 3-chloro derivatives. 

In Table 6.1, butanoic acid is listed as a weaker acid than acetic acid. Why In that table, formic acid is seen to be a stronger acid than acetic acid. Why ... 

Acid anhydrides have structure 58 and are named by recognizing that the structure consists of two carboxylic acid units. The lUPAC rules demand that the two acids be named sequentially, followed by the word anhydride. For anhydride 63 in Table 16.3, one component is derived from butanoic acid and the other from propanoic acid. The names of the acid are listed alphabetically, so the name of 63 is butanoicpropanoic anhydride. For a general rule of naming, list R and R in 63 alphabetically, followed by the word anhydride). Anhydride 63 is an unsymmetrical anhydride because the two acid components are different. If both acid components are identical, it is a symmetrical anhydride such as 64. Using both acid names for this compound leads to diethanoic anhydride, or simply ethanoic anhydride When the single name is used, the anhydride is understood to be symmetrical. Anhydride 64 is derived from ethanoic acid, which has the common name acetic acid, so the common name acetic anhydride is often used for 65. 

Amides such as 60 are viewed structurally as a combination of an amine and an acid, so there is an amine name and an acid name however, amides are treated differently than esters. For primary amides, an -NH2 group is attached to the carbonyl (two hydrogens on N see 60 Ri=R =H) the name of the acid is changed by replacing the oic acid with the word amide. Two examples in Table 16.3 are butanamide 67 and the ethanoic acid (acetic acid) derivative 68. Amide 67 is a butanoic acid derivative in which OH has been replaced by NH2 and the named is butanamide. The lUPAC name of 68 is ethanamide, but as a derivative of acetic acid, its common name of acetamide is used more often. 

The nomenclature for carboxylic acids follows the familiar pattern of adding the functional group name -oic acid to the named hydrocarbon chain except that the common names formic acid and acetic acid are still widely accepted. Thus, formic acid is methanoic acid, acetic acid is ethanoic acid, propionic acid is propanoic acid, and -butyric acid is butanoic acid. The CAS numbers (Chemical Abstract Service, American Chemical Society) for the carboxylic acids are listed in Table 6.1 along with the physical properties. The CAS numbers refer to the major carboxylic acid component. Refer to the Material Safety Data Sheet (MSDS) for CAS numbers of any minor impurities in the solvent. 

In order to determine the taste modulating activity of the identified compounds, triangle tests were performed with the purified compounds dissolved in water (for intrinsic taste) as well as in a model broth solution (for taste modulatory activity), respectively. None of the compounds 1-5 showed any intrinsic taste up to a maximum concentration of 1000 pmol/kg, but all these creatinine derivatives imparted taste modulating activity in model broth by enhancing its thick-sour, brothy taste. The lowest threshold concentration of 76 pmol/kg was found for 4-hydroxy-2-A-(l-methyl-4-oxoimidazolidin-2-ylideneamino) butanoic acid (3), whereas the highest threshold level of 489 pmol/kg was determined for 4-hydroxy-2-77-(l -methyl-4-oxoimidazolidin-2-ylideneamino)pentanoic lactone (4) (Table 1). 

Table 13.15 Catalyst properties and catalytic performance for the ketonization of propanoic acid (PA) or butanoic acid (BA). Reaction conditions temperature 410°C N2 flow 15 cm .min acid feed rate 0.1 cm .min weight of catalyst 1.5 g.

In Table 14.2 we saw the names of compounds with common functional groups. We also use the numbering system where necessary to indicate the position of the functional group in a molecule. For some functional groups no number is needed because the group can only be positioned at the end of a chain. Examples of this include carboxylic acids, such as butanoic acid, and aldehydes, such as pentanal. 

The reactions of OH with butanoic and 2-methylpropanoic acids have each been the subject of one investigation, see table VI-B-10. Zetzsch and Stuhl (1982) reported an ambient temperature value of 1.8 x 10 cm molecule s for the reaction of OH with butanoic acid. Dagaut et al. (1988b) report A = 2.6 x 10 exp(—70/r) cm molecule" s for the reaction of OH with 2-methylpropanoic acid, although a temperature-independent value of 2.1 x 10 cm molecule" s" would also adequately represent the data. Given the paucity of available data, uncertainties of 30% are recommended near 298 K. 

Table VI-B-IO. Rate coefficients (k = Axe cm molecule s ) for reaction of OH with butanoic acid [CH3CH2CH2C(0)0H] and 2-methylpropanoic acid [(CH3)2CHC(0)0H]...

A few comments on the values of r and (r+ - - r ) (cf. Table VIII) are necessary. Increasing hydrocarbon content decreases the hydrophilic property of the anion (cf. formic, acitic, propanoic, butanoic, 3-methyl-butanoic, and benzoic acids) resulting in the decrease of hydration the trend eventually levels off. Hydrophilic substitution increases hydration (cf. acetic, chloroacetic, cyanoacetic, glycolic acids cf. glutaric, succinic, and malonic acids cf. benzoic and salicyclic acids). Also note that r is smallest for benzoic acid and largest for malonic acid. These trends cannot be fortuitous. 

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